CEZDecompressor Class Reference

#include <ezdecompressor.h>

class CEZDecompressor : public CEZZStream

Inherits from

CEZDecompressor
- CEZZStream
  - CBase

Public Member Enumerations
enum	anonymous { EInflateInitlialiserError, EInflateVersionError, EInflateTerminated, EInflateDictionaryError }
enum	anonymous { EMaxWBits }

Public Member Functions
	~CEZDecompressor()
IMPORT_C void	DecompressL(TDes8 &, const TDesC8 &)
IMPORT_C TBool	InflateL()
IMPORT_C CEZDecompressor *	NewL(MEZBufferManager &, TInt)
IMPORT_C CEZDecompressor *	NewL(MEZBufferManager &, const TDesC8 &, TInt)
IMPORT_C CEZDecompressor *	NewLC(MEZBufferManager &, TInt)
IMPORT_C CEZDecompressor *	NewLC(MEZBufferManager &, const TDesC8 &, TInt)
IMPORT_C void	ResetL(MEZBufferManager &)

Inherited Attributes
	CEZZStream::iOutputBufferLength
	CEZZStream::iOutputPointer
	CEZZStream::iStream

Inherited Enumerations
	CEZZStream:@38

Inherited Functions
	CBase::CBase()
	CBase::Delete(CBase *)
	CBase::Extension_(TUint,TAny &,TAny )
	CBase::operator new(TUint)
	CBase::operator new(TUint,TAny *)
	CBase::operator new(TUint,TLeave)
	CBase::operator new(TUint,TLeave,TUint)
	CBase::operator new(TUint,TUint)
	CBase::~CBase()
	CEZZStream::Adler32()const
	CEZZStream::AvailIn()const
	CEZZStream::AvailOut()const
	CEZZStream::CEZZStream()
	CEZZStream::OutputDescriptor()const
	CEZZStream::Progress(TInt)const
	CEZZStream::SetInput(const TDesC8 &)
	CEZZStream::SetOutput(TDes8 &)
	CEZZStream::TotalIn()const
	CEZZStream::TotalOut()const

Detailed Description

The CEZDecompressor class provides in-memory de-compression functions, including integrity checks of the compressed data. This version of the library supports only one compression / de-compression method (deflation / inflation). De-compression can be done in a single step (using DecompressL()) if the buffers are large enough (for example if an input file is mmap'ed), or can be done by repeated calls of the InflateL() function. The source data is de-compressed to the target buffer (both source and target contained within the buffer manager argument).

Note: In this version of the library a windowBits value of 8 is unsupported due to a problem with the window size being set to 256 bytes. Although a value of 8 will be accepted by the CEZCompressor constructors, as it is being changed internally by Zlib from 8 to 9, it will not be possible to use the same value for decompression. This is because the Zlib functions called by the CEZDecompressor constructors do not make the same change internally and as a result a KEZlibErrData is returned when calling InflateL(). It is therefore advised that for this version of the library windowBits of 9 is used in place of 8.

Member Enumeration Documentation

Enum anonymous

Decompression panic values

Enumerator	Value	Description
EInflateInitlialiserError	EUnexpected + 1
EInflateVersionError
EInflateTerminated
EInflateDictionaryError

Enum anonymous

Window Bits - the base two logarithm of the window size (the size of the history buffer)

Enumerator	Value	Description
EMaxWBits	MAX_WBITS

Constructor & Destructor Documentation

~CEZDecompressor ( )

~CEZDecompressor

(

)

Member Function Documentation

DecompressL ( TDes8 &, const TDesC8 & )

IMPORT_C void	DecompressL	(	TDes8 &	aDestination,
			const TDesC8 &	aSource
		)	[static]

De-compresses the data in the given buffer

Parameters
aDestination	the target buffer for the de-compressed data
aSource	the buffer containing the compressed data

Leave Codes
KEZLibErrBuf	There is a problem with the buffer
KEZLIbErrData	There is a problem with the data
...	Any of the system wide error codes

InflateL ( )

IMPORT_C TBool

InflateL

(

)

De-compress the data to the buffer in stages, return value indicates if the de-compression has finalised or if further calls are necessary

Return Value: ETrue if the function must be called again, EFalse if compression is finalised

Leave Codes
KEZlibErrStream	There is a problem with the stream
KEZlibErrBuf	There is a problem with the buffer
KEZlibErrData	There is a problem with the data
KEZlibErrUnexpected	Unexpected programming error
...	Any of the System wide error codes

NewL ( MEZBufferManager &, TInt )

IMPORT_C CEZDecompressor *	NewL	(	MEZBufferManager &	aInit,
			TInt	aWindowBits = EMaxWBits
		)	[static]

Creates a new CEZDecompressor object

Parameters
aInit	buffer manager to handle both input and output buffers
aWindowBits	the base two logarithm of the window size (the size of the history buffer). It should be in the range 8..15 for this version of the library. Larger values of this parameter result in better compression at the expense of memory usage.

Return Value: the new CEZDecompressor object

NewL ( MEZBufferManager &, const TDesC8 &, TInt )

IMPORT_C CEZDecompressor *	NewL	(	MEZBufferManager &	aInit,
			const TDesC8 &	aDictionary,
			TInt	aWindowBits = EMaxWBits
		)	[static]

Overload of CEZDecompressor constructor takes aDictionary argument

Parameters
aInit	buffer manager to handle both input and output buffers
aDictionary	used to initialize the de-compression dictionary from the given byte sequence. The compressor and decompressor must use exactly the same dictionary.
aWindowBits	the base two logarithm of the window size (the size of the history buffer). It should be in the range 8..15 for this version of the library. Larger values of this parameter result in better compression at the expense of memory usage.

Return Value: the new CEZDecompressor object

NewLC ( MEZBufferManager &, TInt )

IMPORT_C CEZDecompressor *	NewLC	(	MEZBufferManager &	aInit,
			TInt	aWindowBits = EMaxWBits
		)	[static]

Creates a new CEZDecompressor object and leaves it on the CleanupStack

Parameters
aInit	buffer manager to handle both input and output buffers
aWindowBits	the base two logarithm of the window size (the size of the history buffer). It should be in the range 8..15 for this version of the library. Larger values of this parameter result in better compression at the expense of memory usage.

Return Value: the new CEZDecompressor object (on the CleanupStack)

NewLC ( MEZBufferManager &, const TDesC8 &, TInt )

IMPORT_C CEZDecompressor *	NewLC	(	MEZBufferManager &	aInit,
			const TDesC8 &	aDictionary,
			TInt	aWindowBits = EMaxWBits
		)	[static]

Overload of CEZDecompressor constructor takes aDictionary argument

Parameters
aInit	buffer manager to handle both input and output buffers
aDictionary	used to initialize the de-compression dictionary from the given byte sequence. The compressor and decompressor must use exactly the same dictionary.
aWindowBits	the base two logarithm of the window size (the size of the history buffer). It should be in the range 8..15 for this version of the library. Larger values of this parameter result in better compression at the expense of memory usage.

Return Value: the new CEZDecompressor object (on the CleanupStack)

ResetL ( MEZBufferManager & )

IMPORT_C void

ResetL

(

MEZBufferManager &

aInit

)

Resets the current de-compression operation, with the new buffer manager

Parameters
aInit	new buffer manager to handle the new input and output buffers

Leave Codes
KEZlibErrStream	There is a problem with the stream
...	Any of the System wide error codes